A continuous process for preparing alkoxysilanes or alkoxypolysiloxanes by reacting chlorosilanes with hydroxyl-containing aliphatic compounds and optionally water, in a column maintained at an elevated temperature and equipped with a reflux condenser is described in U.S. Pat. No. 3,792,071 to Nitzsche et al. In this process, the chlorosilane is introduced at the head of the column and the alcohol is introduced in the gaseous form from below or at a point in the lowest one-third of the length of the column and when water is employed, it is introduced at any desired point along the length of the column, and the reaction product is removed from the column at its lower end or at a point below the point of addition of the alcohol.
In contrast to the process described above, the process of this invention provides higher space-time yields without increasing the hydrogen chloride content of the product. Also, undesirable side reactions, such as the polymerization of silanes having aliphatic multiple bonds, are to a great extent avoided in the present process.
Therefore, it is an object of this invention to provide a continuous process for preparing alkoxysilanes and alkoxypolysiloxanes. Another object of this invention is to provide a process for preparing alkoxysilanes and alkoxypolysiloxanes in which the polymerization of silanes having aliphatic multiple bonds is to a great extent eliminated. Still another object of this invention is to provide a process for preparing alkoxysilanes and alkoxypolysiloxanes which are substantially free of hydrogen chloride. A further object of this invention is to provide a process for preparing alkoxysilanes and alkoxypolysiloxanes having higher space-time yields without increasing the hydrogen chloride content of the product.